Structural and optical properties of as-grown and annealed Alq3 thin films

This work contains investigation results of the structural and optical properties of aluminum (III) tris(8-hydroxyquinoline) - Alq₃ thin films. The films were successfully grown by physical vapor deposition (PVD) technique in high vacuum on transparent (quartz) and semiconductor (n-type silica) substrates kept at room temperature during the deposition process. Selected films were annealed after fabrication in ambient atmosphere for 24 hours at the temperature equal to 50°C, 100°C and 150°C. Spectral properties of these films were examined using transmission, photoluminescence, SGH and THG technique. The experimental spectra were allowed to determine optical constant of the films. Structural properties were investigated by AFM measurements. The Alq₃ films exhibit high structural quality regardless of the annealing process, but the stability of the film can be improved by using an appropriate temperature during the annealing process. We find that the optical properties were strictly connected with the morphology and the annealing process can significantly change the structural properties of the films.